Variable inductive tuner



April 13, 194s.

I C. J. H. VICTOREEN VARIABLE INDUCTIVE TUNER Filed Jan. 8, 1944 2Sheets-Sheet 1 S :IS 1

Tree/way April 13, 1948.

C. ,Ik H. VICTOREEN VARIABLE INDUCTIVE TUNER 2 sheets-sheet 2 Filed Jan.8, 1944 Illl e m /MQ 7 m., Ha. y.. .w e M C PatentedmApr. 13,

UNITED` STATES PATENT OFFICE 2,439,403 VARIABLE INDUCTIVE TUNER CharlesJ. H. Victoreen, Dayton, Ohio Application January 8, 1944, Serial No.517,517 2 Claims.- (Cl. 171-242) (Granted under the act of March 3,1883, as

amended April 30, 1928; 370

The invention described herein may be manufactured and used by or forthe Government for governmental purposes, without the payment to me ofany royalty thereon.

This invention relates to improvements in device for tuning radiofrequency amplifiers.

It is an object of the invention to provide a device for tuningsimultaneously a multiplicity of circuits in a radio frequencyamplifier, said device extending the range of inductance of theamplifier circuit by adjusting a variable slug 23 with sections havingdifferent permeabilities.

A further object is the provision of a device for simultaneously tuninga multiplicity of circuits in a radio frequency amplier and at the sametime providing a band-width adjustable from a few kilocycles to severalmegacycles.

A further object is the provision of a device for varying the inductanceof a circuit by sliding in a coil a core having a plurality of sectionswith different permeabilities.

A further object is the provision of a novel device for wide rangetuning of a tuned radio frequency amplifier in which the desiredcharacteristics are obtained by the use of ganged inductive tuning for aplurality of stages of radio frequency amplification. In accordance withthe invention, the tuning is accomplished by sliding cores of differentpermeabilities within the inductance coils of the interstage'transformers of the amplifier. The cores are ganged by being mounted intandem on a single rod, which enables all of the cores to be movedsimultaneously.

These and other objects are attained by the novel structure andarrangement hereinafter described and illustrated by the accompanyingdrawings, in which Fig. 1 is a plan view of invention.

Fig. 2 is a plan view of the device with the cover removed.

Fig. 3 is a side elevational view of the device.

Fig. 4 is a sectional view taken on the line 4-4 of Fig. 1.

Fig. 5 is a sectional of Fig. 4.

Referring to the drawings, there is shown a casing having a lowersection I and an upper section or cover 2, the casing being divided intoa plurality of shielded compartments 3 in which are mounted interstagetransformers. Positioned in each compartment are supporting frames i5upon which are mounted cylindrical coil forms il of thin insulatingmaterial upon which are closely interwound the primary and secondarywindings I9 and 20 of the transformers.

The tube plate and grid capacities (not shown) normally supply thecapacities with which the primary and secondary coil windings I8, 20respectively are resonant. Also on the form i1 is a device embodying theview taken on the line 5 5 26. By adjusting the tertiary circuit, theband width of the transformer can be controlled.

Extending through forms Il, which are hollow and coaxial, and throughthe compartments 3, is an adjustable core 4. 'Ihe core 4 is composed ofa succession of slugs 22, 23, 24 mounted on a continuous rod 25. Slugs22 are of polyiron or other ferromagnetic material, slug 23 is of brassor similar nonferrous materials, and slug 24 is of a dielectric. Thepolyiron slug 22 and the brass slug 23 are partly cylindrical, fittingsnugly within coil forms Il and partly tapered on one pair of adjoiningends. The dielectric slugs 24 are also cylindrical on their outersurfaces, iilling out the spaces around the tapered portions of slugs22, 23. This construction produces an overall cylindrical structure forcore 4 so that it slides smoothly within the forms I1.

Supported by an end Wall of the casing is a threaded shaft 5 on whichrides a nut I2, Ilxed to a sleeve 21, which in turn is fixed to rod 25.The sleeve 21 has a slot 28 and is prevented from rotation by means of apost 29 positioned in the slot 28. By rotating shaft 5, the sleeve 21and the rod 25 are caused to move longitudinally.

The extreme range of tuning is effected by starting with the cylindricalportion of the polyiron slug 22 wholly within the coil form Il. This isthe position of maximum inductance and low- As the tapered portion ofthe polyiron is slid into the coil form Il, inductances 20, 2| arereduced core begins to enter the coils, the inductance is reduced stillfurther, through the action of induced currents in the brass; andminimum 1nductance is reached when the brass slug illls the In order toprovide a trimmer adjustment to line up all the stages initially and toallow :for variation of capacity from tube to tube, an adjustment isprovided for shifting independently each supporting frame I5 along theaxis of the core 4. In each compartment a screw 30 is prevented fromlongitudinal movement by a nut 3i and spring washer 32. The screw 30threadedly engages a nut 33 which engages a U-shaped member 34 havingone leg longer than the other. The long leg of member 34 engages theupper surface of nut 33 and the shorter leg engages the side of the nut.(See Fig. 4.) The member 34 is pivotally mounted at 6 and has integraltherewith right angularly directed legs 31 carrycross-wise ilts o! thewhich modiilcations ing pins 3G in a slot l5 o! a bracket Il fixed towhich is mounted :lor sliding movement along the lower section i of thecasing. (See Fig. 5.) By rotating the screw 3l, the support .l5 is movedhorizontally. The slots 3l prevent binding oi the pins 30, and the snugpins in the slots 3i hold the frames i5 nrmly in adjusted `positions andpreserve the necessary stability of the amplifier.

The above description is to be considered as illustrative and notlimitative of the invention oi can be made obviously witbout departingfrom the spirit and scope ci the invention as set forth in the appendedclaims. Thinvention having been described, what is claim 1. In anadjustable inductance device having the support I! "a easing, aplurality of trames adiustably car ried by the casing, coil meanscarried by each trame, a core for each coll means. carried by the casingfor supporting and ior simultaneously moving all the cores with respectto the frames: means for adjusting the position of an individual framewith respect to its core comprising a screw carried by the casing. a nuton the screw. a linkage having one end connected to the nut andthe otherend to the frame, so that rotation oi the screw changes the position ofsuch individual frame V11itliuxgspect to its core;

and means 2g 2. In a tuning device for radio apparatus: a casingcontaining a plurality of frames each slidably mounted in the casing; aplurality of tuning means, each corresponding to one of the frames g andincluding two parts which are moved relatively to each other toaccomplish tuning, one of the parts being carried by the casing and theother by means for e i0 the frame; and position-adjusting ach frame,these position-adjusting means including ascrew supported by the casingtogether with a nut and linkage controlled by movement of the screw foradjusting the position of each frame with respect to the casing. CHARLESJ. H. VICTOREEN.

REFERENCES CITED The following references are of record in the E ille ofthis patent:

Number vNumber UNITED STATES PATENTS France Dec. 27, 1922

